Antenna and coupling means therefor



p .9 N. E. LINDENBLAD 2,296,356

ANTENNA AND COUPLING MEANS THEREFOR Filed July 19, 1941 4 Sheets-Sheet l 3 gal 1Q V I I 1b /0 INVENTOR ZVJZXEZ ATTORNEY Sept. 22, 1942- N. E. LINDENBLAD ANTENNA A NDCOUPLING MEANS THEREFOR Filed July 19, 1941 4 Sheets-Sheet 2 A I I ll P 1942- N. E. LINDENBLAD 2,296,356

ANTENNA AND COUPLING MEANS THEREFOR Filed July 19, 1941 4 Sheets-Sheet 5 INVENTOR ATIZORNEY P 22, 1942- I N. E. Li NNNNNN AD 2,296,356

enema Sept. 22, 1942 Ms Ann oourcma amass mmroa Nils E. Lindenblad, Rocky Point, N. Y., who: to

Radio Corporation of America, a corporation of Delaware Application July 19, 1941, Serial No. 403,123

16 Claims. (CL 250--33) The present invention relates to short wave antennas and means for coupling said antennas to an associated transmission line.

An object of the present invention is to provide a radiation origin of radiant energy which polarizes the radiant energy in a plane which 'is homogeneously symmetrical to this origin and which radiates equally in all directions in this same plane.

Another object of the present invention is the production of a uniform current loop resulting in uniform horizontally polarized radiation.

Another object of the present invention is the production of a uniform current loop resulting in uniform radiation in all directions in the plane of the loop.

Another object of the present invention is the production of an antenna which has no tunin characteristic regardless of dimensions. v

Still a further object of the present invention is to provide a novel structure for coupling an antenna to a transmission line.

Still a further object of the present invention is to provide a toroidal current transformer for the purpose of introducing a series EMF without breaking up the continuity of the conductor in which it is desired that the EMF be introduced.

The foregoing objects, and others which may appear from the following detailed description, are obtained by the provision of a radiating structure in the form of a single horizontal loop antenna which is energized by means of a plurality of toroidal coupling transformers interposed between said ring and the energizing means therefor.

The present invention will be more fully understood by reference to the following detailed description, which is accompanied by drawings in which Figure 1 illustrates, partly in section, the application of a coupling arrangement, according to the presentinvention, to a linear half wave dipole radiator, while Figure 2 is a cross-section of Figure 1; Figures 3 and 4 illustrate, partly in section plan and elevation views, the application of the coupling arrangement of Figures 1 and 2 to a horizontal ring radiator; Figures 5, 6, 7 and 8 illustrate modifications of the toroidal couplin arrangements of the foregoing fi es.

Referring, now, to Figures 1 and 2, reference character It indicates a half wave dipole radiator having a substantial cross-section dimension whereby a broad resonance curve is obtained. The dipole It may be supported by, and is energized through, the balanced transmission and I2, having therein inner conductors II and It. Transmission line TL may be connected to a conventional transmitter or other translating means. The inner conductors It and H are extensions of the two inner conductors of the balanced transmission line TL. Inner conductors l3 and It are connected to a toroidal coupling coil l surrounding the dipole It at substantially its midpoint. Connections from one pair of opposite sides of toroid it pass through insulators l8 and I1 and are connected in a parallel relationship to conductor l3. Similarly, another pair of connections to opposite sides of toroid it pass through insulators l8 and I9 and thence to conductor ll.

As will be more clearly seen from Figure 2, toroid i5 is composed of four coils II, 22, 23 and 24, each grounded to dipole It at its midpoint, as indicated by reference character 20. The coils 2! to 24, inclusive, are connected in a series relationship to form toroid l5. Opposite pairs of coils are wound in the same direction and in the opposite direction to adjacent ones. For example,'coils 2|, 23 may be counter-clock-wise wound and coils 22, 24, clock-wise. Currents from transmission line TL flowing through coils 2| to 24, inclusive, induce longitudinal currents along the length of dipole Ill. The longitudinal current flow sets up a radiant energy field in the same way as any conventional dipole antenna. The antenna may, of course, be used for reception as well as transmission.

Figures 3 and 4 illustrate a current ring radiator energized by structure similar to that shown in Figures 1 and 2. The ring radiator 30 is supported from the transmission line TL by means of radial arms 3|, each of which carries an inner conductor 33. Alternate conductors 33 are connected to the central conductor 34 of the transmission line TL and remaining ones to the 'casing 35. Casing 35 is surrounded by a shell 36 which is connected to casing 35 at a distance from the end equal to a quarter of the length of the operating wave. The arrangement of shell 36 .around the end of casing 35 is for the purpose of electrically freeing the end of the casing 35 from ground. This operation is more fully described in my prior applications, Serial #76,!45, filed April 28, 1936, now Patent #2,131,l08; Serial #276,193, filed May 27, 1939, and Serial #183,571, filed January 6, 1938, now Patent #2,238,904, to which reference may be made for a more complete understanding thereof. This portion of the structure forms no essential part of the present line TL, which is divided into two single lines ll 56 invention and is, therefore, not described in of the conductor in the coils.

greater detail here. Conductors 33 are so connected to adjacent coils l in a paired relationship that the current induced in ring 3|! by the current flowing in coils ,I5 is in an additive sense around the ring. The antenna itself, that is ring element 50, does not have any tuning characteristic, regardless of its dimensions if it is fed equally at a sumcient number of places. For a ring havinga diameter of about .6 of a wave, eight equally spaced radial coupling coils are suificient. The diameter of .6 of a wave of ring 30 represents an approach to the first radiation maximum in the plane of the ring. The terminal coil effect of the radiation load and the. toroidal coupling coils represents a loading which is both resistive and inductively reactive. It is, therefore, desirable tobalance out the reactive component of the load. A convenient way in which this may be done is by the provision of compensating reactances 31 in each of the radial transmission arms 3|. The compensating reactance 31 is spaced a quarter wavelength along conductor 33 from toroids I5 and, due to the quarter wave spacing, introduces a reactance equal in magnitude and opposite in sense from that introduced by the toroids. A compensation for the reactance is therefore obtained. Compensating capacities may be directly connected to the toroids if desired. Instead of using the compensating reactances 31, or compensating capacities, the antenna may be composed of a pair of ring radiators connected to transmission line through individual transmission lines which difier in length by an odd multiple of a quarter wavelength, as disclosed in my prior copending application #274,717, filed May 20, 1929. This form of connection causes the reactance introduced by one set of toroids to compensate for the reactance introduced by the other set of toroids. tivity is obtained.

While the ring antenna, as described, does not have any tuning characteristic, due to the changes in the terminating reactances and changes in the wave distribution on the transmission lines with a variation in operating frequency some tuning effects will result. However,

the ring antenna as shown in Figures 3 and 4 has a suflicient band width characteristic to be suitable for sound broadcast using any type of modulation.

While not shown in Figures 3 and 4, the top of shell 36 should be closed by a cap of some sort in order to prevent the entrance of rain, dust, etc., which would tend to upset the operation of the device.

In the previously described antennae the toroidal couplers were directly connected to the transmission line. In the antenna shown in Figures 3 and 4 resonant eflects may occur due to the size of the coils necessary to obtain a good loading being sufficient to allow a non-uniform distribution of voltage and current along the length Within a reasonably wide band of frequencies, these may be compensated for, together with all other inductive reactances by the'use of compensating reactances, as heretofore explained. According to another aspect of the invention, the effect of the non-uniform energy distribution along the conductor lengths of the coupling may be overcome by using couplers of the type shown in the following figures in which the coupling conductor lengths are extremely short compared to the operating wavelength.

Furthermore, a greater vertical direc-.

The coupler shown in Figure 5, which largely overcomes such effects, comprises a closed toroid 55 surrounding a conductor which may correspond to either dipole I0 01 Figure 1 or ring radiator 30 of Figures 3 and 4. The toroid is spaced from conductor l5 by an insulating ring 5|. Energy is coupled to toroid by means of a loop 52 connected to a transmission line as indicated by arrows labeled To transmission line." The toroid coil 55 forms, due to this construction, one turn around its central axis for each layer of windings. If the wire ends of toroid 55 are connected together an endless coil is produced in which current may be induced by loops in a plane parallel to the plane 01 the toroid. Such a loop is loop 52. The current so induced in circulating around the turns of the toroid 55 produces a circular magnetic field which is perpendicular to the field of excitation from the loop 52. If there is no variation in the voltage and current along the length of the excitation loop 52, that is, if the length of the loop is small compared to the operating wavelength, the floating toroid 55 forms a completely non-resonant link due to the uniformity of the magnetic electric field. However, in practice this is not entirely realized and the toroid link assumes resonant characteristics which depend upon the physical dimensions of the winding. Such resonant characteristics may be entirely overcome by utilizing a coupling link such as shown in Figure 6. The coupling link as shown in this figure comprises a series of individual separate loops arranged generally as the windings in a toroid are arranged. The turns are not connected together in series but are maintained in position by being pressed, soldered, brazed or otherwise fastened to an inner conductive ring 66. By setting the individual loops at an angle with the axis of the system they may, nevertheless, be excited by a common coupling loop such as loop 52 of Figure 5. Also, the current flowing in the loops 65 set up a circular magnetic field around the axis of ring 66.

In Figure 7 I have shown a modification of the coupling link of Figure 6 in which the loops forming the link are twisted to provide better coupling to both the primary and secondary. The individual loops 15 have their outer portions twisted so as to be nearly parallel to the direction of current fiow in the surrounding coupling loop, such as 52 of Figure 5. The inner portions of the individual loops which are fastened to ring are twisted to a position parallel to the inner conductor, such as conductor 50 of Figure 5. The primary and secondary circuits, as can readily be seen, have fields which are perpendicular to each other and are completely uncoupled from one another in the absence of the link circuit.

For the sake of mechanical considerations, such as lightning protection and increased mechanical strength, the structure shown in Figure 7 may be further modified as shown in Figure 8. In this modification there is provided an outer ring 84 and an inner ring 85 of substantial axial length. Along each edge of the rings are connected spokes 85 which are so staggered around the periphery of the rings as to simultaneously provide couplings of the type shown in Figure 7 and, also, the inverse type of coupling wherein the coupling loop is within ring 86 and the longitudinal conductor surrounds ring 94. If desired, an excitation loop, such as loop 52 of Figure 5 may be mounted within the coupling unit, that is, between rings 84 and 88. Sheet insulation may be provided at each end of rings I4 and 86 to seal the unit from the effects of adverse weather conditions.

The direction of coupling obtained in Figure '1 is schematically indicated in Figure 8 by means of line 96 wherein current flows as? follows: Starting at the front edge of inner ring 66 the current follows conductor 85 to the front edge of outer ring 8 3 diagonally around ring as to the back edge, thence inwardly along conductors to to the rear edge of inner ring 86 and axially along ring 86 to the startingpoint. The inverse path is indicated by line Hill wherein. starting again at the front edge of ring 85 the current flows diagonally around the surface of ring 68 tothe back edge thereof. Thence it flows out along one of the conductorsfifi to the back edge of ring 34 and longitudinally along ring 6 3 to the front edge and thereafter to the front edge of'riug 66 along another diagonal conductor he.

' The gain in the methods described overthe directly fed toroid or over any hitherto known method of coupling resides partly in the absence of extraneous, undesirable electric and magnetic fields which are intrinsic with the more conventional feed circuit. Another advantage is that the ratio of the transformation and the magnitude of power transfer may be easily determined without encountering difliculties due to using coils so large that the wave distribution enters as a resonance factor. The ease of controlling the transformation ratio may be understood by considering that all of the individual loops work inparallel in the production of the circular mag-- netic field and that by variable overlapping they may be arranged to couple more orless in series with respect to one another when considering the coupling to the feed circuit.

Due to the fact that only the inductive portion of the total tuned circuit is exposed to the weather, such as sleet and lightning and heavy rain, and also due to the novel features of the present invention which takes advantage of the even distribution obtainable by using endless circuit elements, antennae constructed according to the principles set forth in this specification are practically immune to trouble under service 1 conditions.

The coupling devices shown in Figures 5 to 8,

inclusive, while particularly useable with the current ring radiator shown in Figures 3 and 4 and, also, to the dipole of Figures 1 and 2 is-not limited to these uses. They may be used either for coupling to conductors without shunting or series break-in and, also, for the electrodynamic control of electron streams as, for example, disclosed in my copending application, Serial #333,279, filed May 4, 1940.

While I have shown and particularly described several embodiments of' my invention, it is to be distinctly understood that my invention is not limited thereto but that modifications within the scope of my invention may be made.-

I claim:

1. A wide band short wave antenna for radiating horizontally polarized energy substantially uniformly in all directions in a horizontal plane eomprising'a horizontal ring radiator having a 'diameter substantially equal to .601 the operating wavelength and means for simultaneously energizing said radiator at sucha number of equally spaced points around said ring that substantially uniform current distribution is obtaired around said ring.

2. A wide band short wave antenna for radiating horizontally polarized energy substantially uniformly in all directions in a horizontal plane comprising a horizontal ring radiator having a diameter substantially equal to .6 of the operating wavelength and means for simultaneously energizing said radiator at such a number of equally spaced points around said ring that substantially uniform current distribution is obtained around said ring, said energizing means comprising toroidal coupling coils encircling said ring and. coupled to a. transmission line.

3. A wide band short wave antenna for radiating horizontally polarized energy substantially uniformly in all directions in a horizontal plane comprising a horizontal ring radiator having a diameter substantially equal to .6 of the operating wavelength and means for simultaneously energizing said radiator at eight points equally spaced around said ring whereby substantially uniform current distribution is obtained around said ring.

4. In a short wave antenna system having a substantially aperiodic radiator and a. transmission line for connecting said radiator to a translating device, means for coupling said radiator to said transmission line including a toroidal coupling coil surrounding a portion of said radiator and coupled to said transmission line.

5. In an antenna system having a radiator and 'a transmission line for connecting said radiator to a translating device, means for coupling said radiator to said transmission line, including a toroidal coupling coil surrounding a portion of said radiator, connections from opposite sides of said coil to a conductor of said transmission line carrying current of one instantaneous polartransmission line, including a plurality of sub-.

stantially aperiodic toroidal coupling coils encircling said ring at equally spaced points around said ring and coupled to said transmission line.

'7. man antenna system having a horizontal ring radiator and a transmission line for connecting said radiator to a translating device,

means for coupling said radiator to said transmission .line, including a plurality of toroidal coupling coils encircling said ring at equally spaced points around said ring, connections from opposite sides of each of said coils to a conductor of said transmission line carrying current of one instantaneous polarity, connections from midway between said first mentioned connections to another conductor of said transmission line carrying current of opposite instantaneous polarity, said coils being so wound that current flow induced in said ring is additive around said ring.

8. In an antenna system having a horizontal ring radiator and a transmission line for connecting said radiator to a translating device, means for coupling said radiator to said transmission line, including a plurality of toroidal coupling coils' encircling said ring at equally spaced points around said ring, connections from opposite sides of each of said coils to a conductor of said on line carrying current of one instantaneous polarity, connections from midway between said first mentioned connections to another conductor of said transmission line carrying current of opposite instantaneous polarity, said coils being so wound that current flow induced in said ring is additive around said ring and means for compensating for the reactance introduced in said line by said coils.

9. In an antenna system having a horizontal ring radiator and a transmission line for connecting said radiator to a translating device, means for coupling said radiator to said transmission line, including a plurality of toroidal coupling coils encircling said ring at equally spaced points around said ring, connections from opposite sides of each of said coils to a conductor of said transmission line carrying current of one instantaneous polarity, connections from midway between said first mentioned connections to another conductor of said transmission line carrying current of opposite instantaneous polarity, said coils being sowound that current flow induced in said ring is additive around said ring and means for compensating for the reactance introduced in said line by said coils, said last means comprising compensating reactances connected to said transmission line at a distance equal to a quarter of the operating wavelength from said connections to said coupling coils.

10. A link circuit for coupling a pair of conductors lying in mutually perpendicular planes including a plurality of conductive loops arranged in-toroidal formation around one of said conductors, the other of said conductors forming at least one turn around said toroid, said loops being twisted so that their inner portions are substantially parallel to said one conductor and their outer portions are substantially in alignment with said other conductor.

11. A link circuit for coupling a pair of conductors lying in mutually perpendicular planes including a pair of conductive concentric rings around one of said conductors and lying parallel to the plane of said other conductor and connections between the edges of said rings, said connections being arranged to provide an axial current flow in the inner of said rings and a substantially circumferential current flow in the outer of said rings.

12. A link circuit for coupling a pair of conductors lying in mutually perpendicular planes including a pairof conductive concentric rings having their axis parallel to one of said conductors and lying in a plane parallel to the plane or the other of said conductors and connections between the edges of said rings, saidconnections being arranged to provide an axial current flow in the outer of said rings and a substantially circumferential current flow in the inner of said rings.

13. Means for inductively coupling a pair of conductors lying in mutually perpendicular planes including a plurality of conductive loops interposed between said conductors and arranged in a toroidal formation, said loops having portions thereof in inductive relationship with each of said conductors.

14. Means for inductively coupling a pair of conductors lying in mutually perpendicular planes including a plurality of overlapping closed conducting loops connected in parallel and interposed between said conductors and arranged in a toroidal formation, said loops having portions thereof in inductive relationship with each of said conductors.

15. An arrangement for coupling a pair of circuits having magnetic fields which are mutually perpendicular including a plurality of conducting loops arranged in the form of a torus and surrounding a conductor of one of said circuits and a conductor of the other of said circuits surrounding. said torus.

16. An arrangement for coupling a pair of circuits having magnetic fields which are mutually perpendicular including a plurality of conducting loops arranged in the form of a torus and surrounding a conductor of one of said circuits, said loops being arranged in an inductive relationship to a conductor of the other of said circuits.

NILS E. LINDENBLAD. 

